The present invention relates to a transmitter having a phase-locked loop (PLL) circuit which receives a modulation signal and supplies a modulated signal, and an amplifier connected to the output of the PLL circuit.
If a transmitter has a PLL circuit, a transmission frequency can be changed and set to a desired frequency. The output of the PLL circuit is usually amplified by an amplifier connected thereto. To save power, power is supplied to the amplifier only during signal transmission. However, the input impedance of the amplifier fluctuates when the amplifier is turned on. This causes the output frequency of the PLL circuit to also fluctuate, resulting in improper transmission.